Concrete air entrainment too low 1

[McSEpllc]

Hi Everyone,

Today the first segments of many site retaining walls were poured. The air content of the concrete of the wall was tested at 2%.

Specified are:
4,000 psi concrete,
6% air +/- 1.5%,
W/C ratio of 0.4.

The mix has 2.85 cu ft of cement,
1 cu ft of type F fly ash,
10.6 cu ft of 1” coarse aggregate, and
6.4 cu ft of fine aggregate.

The wall in question will be exposed (no veneer), it will not be exposed to de-icing salts.

I consider the particular wall location to be an exposure category F1 (moderate: exposed to freeze thawing with occasional exposure to moisture.) That would require an air entrainment per ACI of 4.5% +/-1.5%, so a low end of 3%.

Is there supplemental testing on air entrainment that can be done on hardened concrete?
Is there a surface treatment that can help?
What would you do?

Thanks!


Eric McDonald, PE
McDonald Structural Engineering, PLLC

 

[Ron]

Yes. Air entrainment amount can be checked on hardened concrete. It can be done as a part of a petrographic examination of hardened concrete.

 

[btv189]

You can do both the petrographic examination and take cores and have simulation tests run on cores for freeze thaw cycles, although this test takes a couple monthes to perform.

 

[darthsoilsguy2]

air void analysis ASTM C457. any lab that offers petrographic should do this. know that there may be multiple trucks in play that have different air contents. even if the testing agent puts a sample location down, it very well could be other places in that pour

waterproofing materials help freeze/thaw by reducing water penetration. If the breaks come well high and ripping it out is not prudent to the owner, a surface application of thoroseal may be in order. it also produces a nice surface.